A battery converts chemical energy into electrical energy using redox reaction in a positive electrode and a negative electrode to extract the electrical energy or converts the electrical energy into the chemical energy to store the chemical energy and is used as a power supply in a variety of devices.
In late years, a battery with high capacity density has increasingly been required along with a rapid permeation of portable electronics devices. In order to meet the demand, a battery using alkali metal ion with a low mass per unit charge has been developed. Among these, a battery using lithium ion has particularly been utilized. Such lithium ion battery uses a lithium-containing heavy metal oxide and a carbon material as an active material of a positive electrode and a negative electrode, respectively and performs charge and discharge of the battery using an insertion reaction and a elimination reaction of lithium ion against these active material.
Such lithium ion battery however uses a heavy metal compound with a high specific gravity particularly as an active material of the positive electrode. Therefore, it is difficult to sufficiently increase a battery capacity per unit mass, so that there has been a problem of difficulty in acting as the battery with a high capacity density for the lithium ion battery.
Consequently, there has been taken an approach to develop a large capacity battery using a more lightweight electrode material. For instance, U.S. Pat. No. 4,833,048 specification and Japanese Patent Publication No.2,715,778 disclose a battery utilizing an electrochemical redox reaction on the basis of production and dissociation of a disulfide bond by means of the use of an organic compound having the disulfide bond as an active material of a positive electrode.
The battery however uses the organic compound consisting of low-mass elements such as sulfur and carbon as an electrode material. Therefore, an effect is obtained for a configuration of a battery with a high capacity density to some extent, and however recombination efficiency of dissociated disulfide bond is low, so that the battery has had a problem of insufficiency in stability of charge and discharge.
A battery using a conductive polymer as an electrode material is also disclosed as a battery using an organic compound as an active material. The battery performs charge and discharge by a doping reaction and dedoping reaction of an electrolytic ion against the conductive polymer, where the doping reaction is defined as a reaction to stabilize by counterion an exciton such as a charged soliton and polaron generated by an electrochemical redox reaction of the conductive polymer and on the other hand, the dedoping reaction is defined as a reverse reaction of the doping reaction, namely a reaction to electrochemically oxidize or reduce the exciton stabilized by the counterion.
U.S. Pat. No. 4,442,187 specification discloses a battery with a positive electrode or a negative electrode consisting of such conductive polymer. The conductive polymer is composed of low-mass elements such as carbon and nitrogen, so that the battery was highly attractive as a battery with a high capacity density.
However in general, the conductive polymer has a behavior that excitons generated by an electrochemical redox reaction are delocalized in wide-ranging areas of conjugated π-electron systems to interact each other. For this reason, there has been a problem that concentration of the generated excitons is limited so that capacity of the battery is restricted. Therefore, the battery whose electrode material is such conductive polymer has been still insufficient in capacity density growth.